[PATCH 4/4] drivers/misc/sgi-gru: fix dereference of ERR_PTR

[Sudip Mukherjee <sudipm.mukherjee@gmail.com>]

gru_alloc_gts() can fail and it can return ERR_PTR(errvalue). We should
not dereference it if it has returned error. And incase it has returned
error then just downgrade the write lock and exit.

Signed-off-by: Sudip Mukherjee <sudip@vectorindia.org>
---
 drivers/misc/sgi-gru/grukservices.c | 3 +++
 1 file changed, 3 insertions(+)

diff --git a/drivers/misc/sgi-gru/grukservices.c b/drivers/misc/sgi-gru/grukservices.c
index a6fd773..369f7fe 100644
--- a/drivers/misc/sgi-gru/grukservices.c
+++ b/drivers/misc/sgi-gru/grukservices.c
@@ -161,6 +161,8 @@ static void gru_load_kernel_context(struct gru_blade_state *bs, int blade_id)
 
 	if (!bs->bs_kgts) {
 		bs->bs_kgts = gru_alloc_gts(NULL, 0, 0, 0, 0, 0);
+		if (IS_ERR(bs->bs_kgts))
+			goto err_gru_alloc_gts;
 		bs->bs_kgts->ts_user_blade_id = blade_id;
 	}
 	kgts = bs->bs_kgts;
@@ -184,6 +186,7 @@ static void gru_load_kernel_context(struct gru_blade_state *bs, int blade_id)
 		bs->kernel_cb = get_gseg_base_address_cb(vaddr, ctxnum, 0);
 		bs->kernel_dsr = get_gseg_base_address_ds(vaddr, ctxnum, 0);
 	}
+err_gru_alloc_gts:
 	downgrade_write(&bs->bs_kgts_sema);
 }
 
-- 
1.9.1